Although I knew Loki wasn't walking us into a rock face, I still couldn't stop my instinctive flinch when my eyes were convinced I was millimetres from smashing my face into unyielding stone. Stumbling, my eyelids closed at the last second, then flashed open to find a dim grey twilight surrounding us.

Loki continued to hold our hands, guiding us forward into a massive cavern. I couldn't tell where the faint light came from. There was no obvious source. Instead, it seemed to emanate from the rock itself. Lacking much in the way of distinguishing features, the walls, floor, and ceiling all had the same nondescript grey tone.

Unnerving in its sameness, the hair stood at the back of my neck.

Indeed, the sole feature in the entire space was three dark tunnel mouths on the far side, faintly discernible due to the colour contrast. As we approached, a rushing, almost roaring sound reached my ears.

It's too quiet.

With the sound emerging from the tunnels, I finally realized what had gooseflesh rising on my skin. Our footsteps made no noise. Even our breathing was utterly silent.

I tapped my foot on the rock under my feet, yet no sound reached my ears. Stomping my foot gave me the same eerie silence. Frowning, I opened my mouth to speak, and Loki caught my eye, shaking his head.

He guided us into a dark tunnel opening on the far right and the sound resolved to something recognizable—water crashing over rock in a torrent.

"We should be okay to talk now, with the river's noise in the canyon masking us," Loki murmured, releasing our hands, but continuing to walk deeper into the tunnel.

"What is it we are not wanting to draw the attention of?" I whispered.

"The hellhounds that guard the Naihe Chasm bridges over the River Styx. The dead have no voices as they pass through greylands until they cross one of the chasm bridges. I don't particularly want to be dog food, do you?" Loki asked, with an amused quirk to one side of his mouth.

Shaking my head, I followed him.

The water's roar grew louder with each step.

"How will we get past the hellhounds?" Shannon asked.

"We only have to pass Cerberus, as he guards the tunnel to the soul gate. Hopefully, he'll be asleep. He doesn't usually bother the souls passing him. This is the main route for the dead to enter Helheim. It's Garm and Modgud that we don't want to attract the attention of. Those hounds guard the tunnels to the demon gate and ghost gate. No one gets through those tunnels without a token from Hades. We're going to need one when we leave with Baldur," Loki said.

"Do I want to know why they are called the demon and ghost gates?" Shannon asked, frowning.

"Hecate, Goddess of Witchcraft, Poisons, and Necromancy, makes her home in Helheim, on the frozen plateau. That part of the realm belongs to her. Like Hades, she is half Vanir and half Jotun, although I'm not sure what race of giant. Her creatures use those gates," Loki explained as we turned a corner in the tunnel and the grey cavern disappeared from view.

"What kind of creatures? Demons and ghosts?" Shannon asked, rubbing her hands over her arms.

I hadn't noticed any change in air temperature, but put my arm around her waist to lend my body heat, drawing a smile from her.

"Remember the spectral white hellhounds with red ears, the Cŵn Annwn that attacked us in the fog on Alfheim? She created them. They feed on the blood of their victims, then guide the spirits here so she can turn them into phantasms to haunt the living. I have no idea how Calleach got a breeding pair from her. But that's not Hecate's only creatures. Midgardian legends about vampires and werewolves are partly based on her flesh-eating vrykolakas, and blood-drinking empousai, although some races from Muspelheim and Nilfheim share those traits as well," Loki said.

Shannon swore, and I agreed.

Those damn hounds were bad enough. Tackling them, as well as vrykolakas and empousai, didn't seem a wise choice. While I'd heard of the creatures, they didn't enter the water realms. I'd never encountered them.

And shells, if I could keep it that way, I'd be fine with missing the experience.

"Why can't we take this tunnel back?" I asked, raising my voice to be heard over the now deafening sound echoing off the rock.

"Charon won't bring us back across the River Styx, and Cerberus watches for anyone going the wrong direction in his tunnel. The only exits from Helheim are through the demon and ghost gates. But since we are bribing Hades to exchange the power module for Baldur, we shouldn't have an issue getting a token from him," Loki replied. He winced and held a hand to his temple for the next couple of steps.

I didn't think the water's roar was that loud. Frowning, I opened my mouth to shout a question, but in the next step, the tunnel turned and opened into a spectacular gorge.

On the far side, at least twenty metres away, shining obsidian rock walls stretched to either side of a dark tunnel opening. Unable to resist, I stepped to the end to look. The silvery flash of water was a long, long way down from the narrow rock bridge, not even two metres wide, that joined the two sides. In the distance, two more bridges also spanned the chasm. From here, they looked like frail, thin arches of rock.

Loki took the lead, striding quickly across the span with an odd hiccup to his usually fluid movement. He peered into the tunnel opening, then beckoned to us. Shannon followed after him, stumbling partway across. Close behind her, I went to catch her and found my limbs weakening. It was like moving through syrup, and I halted in the middle of the bridge, trying to see what was wrong with my feet.

"Elatha! Get off the bridge," Loki said, rushing onto it to tug my uncooperative body forward.

Shells, I was exhausted. Every part of me wanted to sleep. Just curl up into the corner and close my eyes for a few minutes.

Water splashed my face, and I sputtered as Loki tugged me into the tunnel.

"What was that for?" I asked Shannon.

She recapped her water bottle. "We needed to revive you."

"The River Styx leaches energy when you cross it or spend too much time by its banks. If you touch or consume the water itself, it will send you into a berserker fury. Don't spend any longer on bridges crossing rivers of the underworld than you absolutely must. Only a few waters are safe for your Atlantean powers," Loki said, handing me a seaweed roll to eat.

Chewing it as we walked, it took me a few minutes to regain my wits enough to realize both Shannon and Loki were also eating. Huh. Not just me, then. We each consumed a second, then a third, before my energy returned and we picked up our pace.

Did we pack enough food?

Normally, one roll would be sufficient for an entire day. We might be getting into Shannon's seeds sooner than I could have predicted.

In the midst of calculating how many days of food we had with us, I didn't notice the massive dark shape coming towards us until Loki pressed me against the wall.

Hot, sulphurous breath wafted through the air with a sharp acidic afternote. The scrape of claws on rock came closer and closer until eyes like black flame appeared.

My pulse pounded like a drumbeat in my ears.

Breath catching, the largest black hellhound I'd ever seen turned to look at us. Head easily half a metre in size, with pointed ears and jaw open, tongue hanging out, I couldn't help but notice the bits of ragged cloth and flesh stuck between those lethal dagger-like teeth.

I pressed my back harder against the rock, wishing I could sink inside the black walls.

Cerberus snorted at each of us, drool spraying in long slimy strings, before it turned to continue towards the bridge.

We stayed frozen until it disappeared from sight. Hearing a soft exhale from Shannon, I finally released my own breath. My hand shook as I wiped the slime from my face.

"Yeah, let's not make the enormous hellhound angry," I whispered.

"Did you see its mouth?" Shannon asked.

I shuddered.

Loki put his hand on our backs to urge us onward. "Yes. Cerberus eats those who try to go back through this tunnel, or who don't have coin for Charon to ferry them across the river."

A rough-hewn staircase appeared to descend in front of us, and we started down. With uneven risers taller than usual, the stairs hadn't been built for our legs. I guess Hades didn't care if his souls tripped on their way down.

Loki caught himself on the wall and winced, pausing for a few seconds before continuing. He wiped his hand on his pants.

"What is this grey-orange growth? Some form of lichen or mold?" Shannon asked, pointing to the oddly coloured lumpy smear on the uneven rock wall where Loki's hand had broken some of it.

"It's a toxic mold. Try not to touch it," Loki said, frowning at his fingers before a flash of fire rippled over them.

With the challenge of navigating the stairs so I didn't tumble down them, I hadn't noticed the change in the walls from the medium grey granite and occasional obsidian layer to the rougher and darker basalt. Here and there, the orange mold grew, and I drew my hand back before I touched it.

As we descended, it grew more and more prevalent, covering the walls in large multiple metre-wide swaths. The air also seemed heavier, and I tasted ash on my tongue, gritty and sulphurous.

An orange-red glow highlighted the base of the stairs. Once at the bottom, we passed through an archway and out into a fiery landscape.